a. Field of the Invention
The present invention relates to an optical connector for use in a fibre optic communications system, and particularly an expanded beam optical connector for connecting optical fibres.
b. Related Art
An optical fibre communications system may need to be used in a harsh environment where the connector may be subject to impacts, dirt or extremes of temperature and moisture. One application where optical connectors are used in a harsh environment is in the broadcast industry, where cameras or sound equipment are joined to other electronic equipment by means of fibre optic cables extending across open spaces. The cables may be joined together with optical connectors that may have to lie on the open ground where dirt or mud may find their way into the connector.
One known way to increase the reliability of an optical connector is to make use of an expanded collimated optical beam which is projected between mating connector portions. Then, if dirt or moisture comes between the connector portions, this may only obscure or degrade a portion of the expanded beam between the mated connector portions. The expanded size of the expanded beam relative to the dimensions of the connector portions also reduces the need for high mechanical precision in the connector portions.
An example of such an expanded beam optical connector is disclosed in patent document WO 2007/119036. This document discloses an optical connector in which an optical fibre is held within a ferrule and the stub and ferrule sub-assembly is then secured in place with respect to a ball lens solely by means of an adhesive that partially fills a void within a connector housing. The adhesive, which also holds the lens in place is introduced into the void and cured following an alignment process in which the ferrule and stub sub-assembly is dynamically aligned with respect to the ball lens until the correct optical coupling has been achieved.
Such a connector can be used with optical fibre cables having a plurality of individual optical fibres, each of which leads to a corresponding lens within the connector and a corresponding expanded collimated beam between the connector portions.
Although such a connector is robust and economical, it takes considerable time and expense in manufacture to align the lens with respect to the ferrule and stub sub-assembly. This is owing mainly to the high cost of micromanipulators capable of moving the sub-assembly along three orthogonal axes as well as rotation about one or two axes, and also by the necessity to hold the alignment in place until the adhesive has properly cured.
It is an object of the present invention to provide a more convenient expanded beam optical connector.